In recent years, attention has been drawn to optical coherence tomography (OCT) which is used to form images representing the surface morphology and the internal morphology of an object using light beams emitted from a laser light source or the like. Since OCT does not have invasiveness to human body as X-ray CT (Computed Tomography) does, development of application of OCT in medical field and biology field is particularly expected. For example, in the field of ophthalmology, OCT apparatuses have been put to practical use for forming images of the fundus, the cornea, etc. and measuring the intraocular distance such as the axial length.
It is known that various artifacts are mixed in the image of an object obtained using OCT. In particular, the complex conjugate artifact is depicted in the image acquired with Fourier domain OCT. The complex conjugate artifact is the imaginary image that appears on the opposite side of the real image with respect to the zero delay position where the optical path length (OPL) of the measurement light applied to the object is equal to the optical path length of the reference light. For example, by forming a cross sectional image from the real image that appears on one side of the range (e.g., on the plus range) with respect to the zero delay position, it is possible to acquire a cross sectional image of the object with high image quality in a narrow depth range. Also, for example, by removing the complex conjugate artifact to form a cross sectional image, it is possible to acquire a cross sectional image of the object in the full range.
A method for acquiring a cross sectional image of an object in the full range by removing the complex conjugate artifact is disclosed, for example, in the following document: S. Witte, M. Baclayon, E. J. G. Peterman, R. F. G. Toonen, H. D. Mansvelder, and M. L. Groot, “Single-shot two-dimensional full-range optical coherence tomography achieved by dispersion control”, OPTICS EXPRESS, Jul. 6, 2009, Vol. 17 (No. 14), pp. 11335-11349.